Copper today: twisted pair

Early telephone lines picked up everything around them: the hum of power lines, the clicks of telegraphs, even fragments of other people's conversations. In 1881 Alexander Graham Bell was granted US patent 244,426 for a cable of wire pairs, each pair a complete circuit, arranged so that each wire sat at the same distance from the others. Twisting the two wires of a pair together, he wrote, was the preferred way to get that balance.

Open any Ethernet cable today and you will find the same idea: four pairs of thin copper wire, each pair twisted around itself.